The invention is concerned with a horn in which sound is produced by a diaphragm set in rapid vibration by appropriate electromagnetic means, and in which the sound is amplified by an acoustic conduit. The horn of the invention has particular application in automatic fire and burglar alarm systems, as mentioned above. As also mentioned above, a feature of the horn of the invention is that it includes a self-contained solid state drive and cut-off circuit, so that it is merely necessary to connect the unit into an automatic alarm system, and the unit provides its own drive power and automatic cut-off.
A particular commercial embodiment of the horn of the invention has been constructed, and the constructed embodiment has a 12-volt direct current rating, and draws a maximum of 850 milliamps. The constructed unit develops a sound intensity of about 104 Db at 10 feet. The cut-off timer circuit in the constructed embodiment is timed to de-activate the horn automatically 300 seconds .+-.36 seconds after the unit has been activated. The foregoing specifications, of course, are given merely by way of example, and are not intended to limit the invention in any way.